Increasing the scope of local purges of structures associated with address translation

ABSTRACT

Increasing the scope of local purges of structures associated with address translation. A hardware thread of a physical core of a machine configuration issues a purge request. A determination is made as to whether the purge request is a local request. Based on the purge request being a local request, entries of a structure associated with address translation are purged on at least multiple hardware threads of a set of hardware threads of the the machine configuration.

BACKGROUND

One or more aspects relate, in general, to processing within a computingenvironment, and in particular, to processing associated with addresstranslation data structures of a virtual environment.

In computing environments that support virtualization technology, anoperating system may be running on a virtual machine on a processor thatsupports multiple levels of address translation tables. In such anenvironment, the operating system is a guest of a hypervisor alsoexecuting in the computing environment.

Further, in such environments, dynamic address translation (DAT) may beperformed during a memory reference to translate a virtual address intoa corresponding real or absolute address. This translation typicallyincludes a walk, referred to as a page or DAT walk, of multiple levelsof address translation tables in order to determine the real address.This is time consuming, and thus, to improve performance for futuretranslation requests, the virtual address to real or absolute addressmapping is stored in an entry of a structure associated with addresstranslation, such as a translation look-aside buffer (TLB) or other suchstructure.

The translation look-aside buffer is a cache used by the memorymanagement hardware to improve virtual address translation speed. Thenext time translation for a virtual address is requested, the TLB ischecked. If the translation is in the TLB, the real or absolute addressis retrieved from the TLB. Otherwise, the DAT walk is performed onceagain.

At times, it is necessary to purge some or all of the TLB entries usedby a particular processor. Managing this purging is a complex task andmay negatively affect system performance.

SUMMARY

Shortcomings of the prior art are overcome and additional advantages areprovided through the provision of a computer program product forfacilitating processing in a computing environment. The computer programproduct includes a storage medium readable by a processing circuit andstoring instructions for execution by the processing circuit forperforming a method. The method includes issuing, by a hardware threadof a physical core of a machine configuration, a purge request;determining whether the purge request is a local request; and purging,based on the purge request being a local request, one or more entries ofa structure associated with address translation on at least multiplehardware threads of a set of hardware threads of the machineconfiguration. This increases the scope of local purging, and maydecrease overall purging, thereby increasing system performance.

In one example, the purging the one or more entries of the structureassociated with address translation includes purging one or more entriesof the structure associated with address translation associated with aparticular page of memory specified by the purge request. As an example,the structure associated with address translation is a translationlook-aside buffer.

In one example, the issuing the purge request includes issuing aninvalidate instruction, the invalidate instruction indicating the purgerequest. As examples, the invalidation instruction includes aninstruction selected from the group consisting of: an invalidate pagetable entry instruction, an invalidate dynamic address translation tableentry instruction, and a compare and replace dynamic address translationtable entry instruction.

In one example, the method further includes checking, based on the purgerequest being a local request, whether a purge has already beenperformed on the hardware threads of the set of hardware threads exceptfor the hardware thread issuing the purge request; and performing thepurging, based on the checking indicating the purge has not already beenperformed.

Further, the method may include determining, based on performing thepurging, whether the purge request is a request to purge specific guestentries; and setting a purge done indicator based on the purge requestnot being a request to purge specific guest entries.

In one example, the method further includes entering, by the hardwarethread, Start Interpretative Execution (SIE) on the physical core;determining, based on entering SIE, whether a guest executing on thehardware thread last ran on a thread within the set of threads; andrefraining, based on determining the guest last ran on a thread withinthe set of threads, from purging guest entries of the structureassociated with address translation.

Moreover, in one example, based on determining the guest did not lastrun on a thread within the set of threads, purge guest entries of thestructure associated with address translation on threads of the set ofthreads, and set a purge done indicator.

The purging on the at least multiple threads reduces purging to beperformed on Start Interpretative Execution entry of the hardwarethread.

Computer-implemented methods and systems relating to one or more aspectsare also described and claimed herein. Further, services relating to oneor more aspects are also described and may be claimed herein.

Additional features and advantages are realized through the techniquesdescribed herein. Other embodiments and aspects are described in detailherein and are considered a part of the claimed aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more aspects are particularly pointed out and distinctly claimedas examples in the claims at the conclusion of the specification. Theforegoing and objects, features, and advantages of one or more aspectsare apparent from the following detailed description taken inconjunction with the accompanying drawings in which:

FIG. 1 depicts one example of a virtual computing environment toincorporate and use one or more aspects of a purging facility, inaccordance with an aspect of the present invention;

FIG. 2A depicts another example of a computing environment toincorporate and use one or more aspects of a purging facility, inaccordance with an aspect of the present invention;

FIG. 2B depicts further details of the memory of FIG. 2A;

FIG. 3A depicts one example of address translation;

FIG. 3B depicts another example of address translation;

FIG. 3C depicts one example of a translation look-aside buffer, inaccordance with an aspect of the present invention;

FIG. 4A depicts one example of a format of an Invalidate Page TableEntry (IPTE) instruction, in accordance with an aspect of the presentinvention;

FIG. 4B depicts one example of the contents of a register used by theIPTE instruction of FIG. 4A, in accordance with an aspect of the presentinvention;

FIG. 4C depicts one example of the contents of a mask used by the IPTEinstruction of FIG. 4A, in accordance with an aspect of the presentinvention;

FIG. 4D depicts one example of the contents of another register used bythe IPTE instruction of FIG. 4A, in accordance with an aspect of thepresent invention;

FIG. 4E depicts one example of the contents of yet another register usedby the IPTE instruction of FIG. 4A, in accordance with an aspect of thepresent invention;

FIG. 5 depicts one embodiment of logic to service a guest invalidationor purge request;

FIG. 6 depicts another embodiment of logic to service a guestinvalidation or purge request, in accordance with an aspect of thepresent invention;

FIG. 7 depicts one embodiment of logic to manage a translationlook-aside buffer on Start Interpretative Execution (SIE) entry;

FIG. 8 depicts another embodiment of logic to manage a translationlook-aside buffer on SIE entry, in accordance with an aspect of thepresent invention;

FIG. 9 depicts yet another embodiment of logic to service a guestinvalidation or purge request, in accordance with an aspect of thepresent invention;

FIG. 10 depicts another embodiment of logic to manage a translationlook-aside buffer on SIE entry, in accordance with an aspect of thepresent invention;

FIGS. 11A-11C depict further details of processing associated withservicing purge requests in a computing environment, in accordance withan aspect of the present invention;

FIG. 12 depicts one embodiment of a cloud computing node;

FIG. 13 depicts one embodiment of a cloud computing environment; and

FIG. 14 depicts one example of abstraction model layers.

DETAILED DESCRIPTION

In computing environments that support virtual memory, a memorymanagement technique, referred to as paging, is used to retrieve blocksof memory (e.g., pages) from secondary storage to be used in mainmemory. Further, due to physical memory constraints, chosen blocks ofmemory may be returned (i.e., paged-out) to secondary storage.

As a result of paging-out blocks of memory, address translationstructure entries (e.g., page table entries, region table entries and/orsegment table entries) associated with the blocks of memory beingpaged-out may be invalidated. Additionally, corresponding entries ofstructures associated with address translation (e.g., translationlook-aside buffer entries) may be purged.

In accordance with an aspect of the present invention, a capability isprovided to increase the scope of local purges of structures associatedwith address translation, such as translation look-aside buffers. Byincreasing the scope of local purges in one aspect, purges at othertimes, such as on Start Interpretative Execution entry, are decreased.Further, the number of entries to be purged on SIE entry may also bedecreased. The decreasing of these purges enables overall purging to bedecreased and allows system performance to be increased.

One example of a computing environment to incorporate and use one ormore aspects of a purging facility is described with reference toFIG. 1. Referring to FIG. 1, in one example, a computing environment 100is based on the z/Architecture, offered by International BusinessMachines (IBM®) Corporation, Armonk, N.Y. The z/Architecture isdescribed in an IBM Publication entitled “z/Architecture—Principles ofOperation,” Publication No. SA22-7832-10, 11^(th) Edition, March 2015,which is hereby incorporated by reference herein in its entirety.Z/ARCHITECTURE, IBM, Z/VM and Z/OS (referenced herein) are registeredtrademarks of International Business Machines Corporation, Armonk, N.Y.Other names used herein may be registered trademarks, trademarks orproduct names of International Business Machines Corporation or othercompanies.

In another example, the computing environment is based on the PowerArchitecture, offered by International Business Machines Corporation,Armonk, N.Y. One embodiment of the Power Architecture is described in“Power ISA™ Version 2.07B,” International Business Machines Corporation,Apr. 9, 2015, which is hereby incorporated herein by reference in itsentirety. POWER ARCHITECTURE is a registered trademark of InternationalBusiness Machines Corporation, Armonk, N.Y., USA.

Computing environment 100 includes a central processor complex (CPC) 102providing virtual machine support. CPC 102 is coupled to one or moreinput/output (I/O) devices 106 via one or more control units 108.Central processor complex 102 includes, for instance, a processor memory104 (a.k.a., main memory, main storage, central storage) coupled to oneor more central processors (a.k.a., central processing units (CPUs))110, and an input/output subsystem 111, each of which is describedbelow.

Processor memory 104 includes, for example, one or more virtual machines112, a virtual machine manager, such as a hypervisor 114, that managesthe virtual machines, and processor firmware 115. One example ofhypervisor 114 is z/VM®, offered by International Business MachinesCorporation, Armonk, N.Y. The hypervisor is sometimes referred to as thehost. Further, as used herein, firmware includes, e.g., the microcodeand/or millicode of the processor. It includes, for instance, thehardware-level instructions and/or data structures used inimplementation of higher level machine code. In one embodiment, itincludes, for instance, proprietary code that is typically delivered asmicrocode that includes trusted software or microcode specific to theunderlying hardware and controls operating system access to the systemhardware.

The virtual machine support of the CPC provides the ability to operatelarge numbers of virtual machines 112, each capable of operating withdifferent programs 120 and running a guest operating system 122, such asLinux. Each virtual machine 112 is capable of functioning as a separatesystem. That is, each virtual machine can be independently reset, run aguest operating system, and operate with different programs. Anoperating system or application program running in a virtual machineappears to have access to a full and complete system, but in reality,only a portion of it is available.

Processor memory 104 is coupled to central processors (CPUs) 110, whichare physical processor resources assignable to virtual machines. Forinstance, virtual machine 112 includes one or more logical processors,each of which represents all or a share of a physical processor resource110 that may be dynamically allocated to the virtual machine. In oneembodiment, central processor 110 includes a purging facility 130 used,as described herein, to purge entries in structures associated withaddress translation.

Additionally, in one embodiment, each CPU 110 is a hardware threadexecuting within a processing core (a.k.a., core) 132. A core includesone or more threads, and in this example, core 132 includes fourhardware threads. In other examples, the computing environment mayinclude one or more cores, and each core may include one or morehardware threads.

Further, processor memory 104 is coupled to an I/O subsystem 111.Input/output subsystem 111 directs the flow of information betweeninput/output control units 108 and devices 106 and main storage 104. Itis coupled to the central processing complex, in that it can be a partof the central processing complex or separate therefrom.

In this particular example, the model of virtual machines is a V=Vmodel, in which the real or absolute memory of a virtual machine isbacked by host virtual memory, instead of real or absolute memory. Eachvirtual machine has a contiguous virtual memory space. The physicalresources are managed by host 114, and the shared physical resources aredispatched by the host to the guest operating systems, as needed, tomeet their processing demands. This V=V virtual machine (i.e., pageableguest) model assumes that the interactions between the guest operatingsystems and the physical shared machine resources are controlled by thehost, since the large number of guests typically precludes the host fromsimply partitioning and assigning the hardware resources to theconfigured guests.

In one embodiment, the host (e.g., z/VM) and processor (e.g., System z)hardware/firmware interact with each other in a controlled cooperativemanner in order to process guest operating system operations withoutrequiring the transfer of control from/to the guest operating system andthe host. Guest operations can be executed directly without hostintervention via a facility that allows instructions to beinterpretively executed for the guest, including a pageable storage modeguest. This facility provides an instruction, Start InterpretiveExecution (SIE), which the host can issue, designating a control blockcalled a state description which holds guest (virtual machine) state andcontrols, such as execution controls and mode controls. The instructionplaces the machine into an interpretive-execution mode in which guestinstructions and interruptions are processed directly, until a conditionrequiring host attention arises. When such a condition occurs,interpretive execution is ended, and either a host interruption ispresented, or the SIE instruction completes storing details of thecondition encountered; this latter action is called interception.

Another example of a computing environment to incorporate and use one ormore aspects of the purging facility is described with reference to FIG.2A. In this example, a computing environment 200 includes, for instance,a native central processing unit (CPU) 202, a memory 204, and one ormore input/output devices and/or interfaces 206 coupled to one anothervia, for example, one or more buses 208 and/or other connections. Asexamples, computing environment 200 may include a z Systems server, aPowerPC processor or a Power Systems server offered by InternationalBusiness Machines Corporation, Armonk, N.Y.; an HP Superdome with IntelItanium II processors offered by Hewlett Packard Co., Palo Alto, Calif.;and/or other machines based on architectures offered by InternationalBusiness Machines Corporation, Hewlett Packard, Intel, Oracle, orothers.

Native central processing unit 202 includes one or more native registers210, such as one or more general purpose registers and/or one or morespecial purpose registers used during processing within the environment,as well as a purging facility 211. These registers include informationthat represents the state of the environment at any particular point intime.

Moreover, native central processing unit 202 executes instructions andcode that are stored in memory 204. In one particular example, thecentral processing unit executes emulator code 212 stored in memory 204.This code enables the computing environment configured in onearchitecture to emulate one or more other architectures. For instance,emulator code 212 allows machines based on architectures other than thez/Architecture, such as PowerPC processors, Power Systems servers, HPSuperdome servers or others, to emulate the z/Architecture and toexecute software and instructions developed based on the z/Architecture.

Further details relating to emulator code 212 are described withreference to FIG. 2B. Emulated instructions 250 stored in memory 204comprise software instructions (e.g., correlating to machineinstructions) that were developed to be executed in an architectureother than that of native CPU 202. For example, emulated instructions250 may have been designed to execute on a z/Architecture processor, butinstead, are being emulated on native CPU 202, which may be, forexample, an Intel Itanium II processor. In one example, emulator code212 includes an instruction fetching routine 252 to obtain one or moreemulated instructions 250 from memory 204, and to optionally providelocal buffering for the instructions obtained. It also includes aninstruction translation routine 254 to determine the type of emulatedinstruction that has been obtained and to translate the emulatedinstruction into one or more corresponding native instructions 256. Thistranslation includes, for instance, identifying the function to beperformed by the emulated instruction and choosing the nativeinstruction(s) to perform that function.

Further, emulator code 212 includes an emulation control routine 260 tocause the native instructions to be executed. Emulation control routine260 may cause native CPU 202 to execute a routine of native instructionsthat emulate one or more previously obtained emulated instructions and,at the conclusion of such execution, return control to the instructionfetch routine to emulate the obtaining of the next emulated instructionor a group of emulated instructions. Execution of the nativeinstructions 256 may include loading data into a register from memory204; storing data back to memory from a register; or performing sometype of arithmetic or logic operation, as determined by the translationroutine.

Each routine is, for instance, implemented in software, which is storedin memory and executed by native central processing unit 202. In otherexamples, one or more of the routines or operations are implemented infirmware, hardware, software or some combination thereof. The registersof the emulated processor may be emulated using registers 210 of thenative CPU or by using locations in memory 204. In embodiments, emulatedinstructions 250, native instructions 256 and emulator code 212 mayreside in the same memory or may be disbursed among different memorydevices.

The computing environments described herein support architecturalfunctions, such as dynamic address translation (DAT). With appropriatesupport by an operating system, the dynamic address translation facilitymay be used to provide to a user a system in which storage appears to belarger than the main storage (a.k.a., main memory) which is available inthe configuration. This apparent main storage is referred to as virtualstorage, and the addresses used to designate locations in the virtualstorage are referred to as virtual addresses. The virtual storage of auser may far exceed the size of the main storage which is available inthe configuration and normally is maintained in auxiliary storage (e.g.,storage not directly addressable). The virtual storage is considered tobe composed of blocks of addresses, called pages. Only the most recentlyreferred to pages of the virtual storage are assigned to occupy blocksof physical main storage (e.g., random access memory (RAM)). As the userrefers to pages of virtual storage that do not appear in main storage,they are brought in to replace pages in main storage that are lesslikely to be needed. The swapping of pages of storage may be performedby the operating system without the user's knowledge.

Moreover, in virtual computing environments, the interpretativeexecution architecture provides a storage mode for absolute storagereferred to as a pageable storage mode. In pageable storage mode,dynamic address translation at the host level is used to map guest mainstorage. The host has the ability to scatter the real storage ofpageable storage mode guests to usable frames anywhere in host realstorage by using the host DAT, and to page guest data out to auxiliarystorage. This technique provides flexibility when allocating realmachine resources while preserving the expected appearance of acontiguous range of absolute storage for the guest.

A virtual machine environment may call for application of DAT multipletimes: first at the guest level, to translate a guest virtual addressthrough guest managed translation tables into a guest real address, andthen, for a pageable guest, at the host level, to translate thecorresponding host virtual address to a host real address.

A sequence of virtual addresses associated with virtual storage iscalled an address space, and the dynamic address translation facilitymay be used to provide a number of address spaces. These address spacesmay be used to provide degrees of isolation between users. Such supportcan include a completely different address space for each user, thusproviding complete isolation, or a shared area may be provided bymapping a portion of each address space to a single common storage area.Also instructions are provided which permit a semi-privileged program toaccess more than one such address space. Dynamic address translationprovides for the translation of, for instance, virtual addresses frommultiple different address spaces without requiring that the translationparameters in the control registers be changed.

Dynamic address translation is the process of translating a virtualaddress during a storage reference into the corresponding real orabsolute address. Dynamic address translation may be specified forinstruction and data addresses generated by the CPU. The real orabsolute address that is formed by dynamic address translation, and theabsolute address that is then formed by prefixing, in one embodiment,are 64 bits in length. The virtual address may be a primary virtualaddress, a secondary virtual address, an access register (AR)-specifiedvirtual address, or a home virtual address. The addresses are translatedby means of the primary, the secondary, an AR-specified, or the homeaddress space control element (ASCE), respectively. After selection ofthe appropriate address space control element, the translation processis the same for all of the four types of virtual addresses. An addressspace control element may be a segment table designation or a regiontable designation. A segment table designation or region tabledesignation causes translation to be performed by means of tablesestablished by the operating system in real or absolute storage.

In the process of translation when using a segment table designation ora region table designation, three types of units of information arerecognized—regions, segments, and pages. The virtual address,accordingly, is divided into four fields. In one example, bits 0-32 arecalled the region index (RX), bits 33-43 are called the segment index(SX), bits 44-51 are called the page index (PX), and bits 52-63 arecalled the byte index (BX). The RX part of a virtual address is itselfdivided into three fields. Bits 0-10 are called the region first index(RFX), bits 11-21 are called the region second index (RSX), and bits22-32 are called the region third index (RTX), in one embodiment.

One example of translating a virtual address to a real address isdescribed with reference to FIG. 3A. This process is referred to hereinas a DAT walk (or a page walk) in which the address translation tablesare walked to translate one address (e.g., a virtual address) to anotheraddress (e.g., a real address). In this example, an address spacecontrol element (ASCE) 300 includes a table origin 302, as well as adesignation type (DT) control 304, which is an indication of a startlevel for translation (i.e., an indication at which level in thehierarchy address translation is to begin). Using table origin 302 andDT 304, the origin of a particular table is located. Then, based on thetable, bits of the virtual address are used to index into the specifictable to obtain the origin of the next level table. For instance, if theregion first table (RFT) 306 is selected, then bits 0-10 (RFX) 308 ofthe virtual address are used to index into the region first table toobtain an origin of a region second table (RST) 310. Then, bits 11-21(RSX) 312 of the virtual address are used to index into region secondtable 310 to obtain an origin of a region third table (RTT) 314.Similarly, bits 22-32 (RTX) 316 of the virtual address are used to indexinto region third table 314 to obtain an origin of a segment table 318.Then, bits 33-43 (SX) 320 of the virtual address are used to index intosegment table 318 to obtain an origin of page table 322, and bits 44-51(PX) 324 of the virtual address are used to index into page table 322 toobtain a page table entry (PTE) 325 having a page frame real address(PFRA) 326. The page frame real address is then combined (e.g.,concatenated) with offset 328 (bits 52-63) to obtain a real address.Prefixing may then be applied to obtain the corresponding absoluteaddress.

Another example of address translation is described with reference toFIG. 3B. In this example, a DAT walk is performed to translate aninitial guest virtual address to a final host real address. In thisexample, address space control element (ASCE) 300 is a guest addressspace control element, and DT 304 of ASCE 300 indicates that guesttranslation determined by guest address translation structures 360 is tostart at region first table 306 pointed to by table origin 302. Thus,the appropriate bits of the initial guest virtual address (e.g., RFX308) are used to index into region first table 306 to obtain a pointerof an entry of the region first table. The address of the region firsttable entry (RFTE) is a guest real or absolute address. This guest realor absolute address, with the main storage origin and limit applied,corresponds to a host virtual address. This intermediate host virtualaddress is then translated using host address translation structures370. In particular, address space control element (ASCE) 350 is a hostaddress space control element used to indicate a start level fortranslation in host address translation structures 372. Based on thestart level (e.g., region first table) indicated by DT 354 of ASCE 350,the particular bits of the host virtual address are used to index intothe indicated table with table origin 352 to be used for translationusing host address translation structure 372, as described withreference to FIG. 3A. The translation of the host virtual addresscorresponding to the guest RFTE continues until a host page frame realaddress (PFRA) 374 a is obtained.

Data at the intermediate host page frame real address is a pointer tothe next level of guest address translation structures (e.g., guestregion second table 310, in this particular example), and translationcontinues, as described above. Specifically, host address translationstructures 376, 378, 380 and 382 are used to translate the intermediatehost virtual addresses associated with the guest region second table310, region third table 314, segment table 318 and page table 322,respectively, resulting in host PFRAs 374 b, 374 c, 374 d and 374 e,respectively. Host page frame real address 374 e includes the address ofa guest page table entry 325. Guest page table entry 325 includes aguest page frame real address 326, which is concatenated with the offsetfrom the initial guest virtual address to obtain the corresponding guestabsolute address. In some cases, the main storage origin and limit arethen applied to calculate the corresponding host virtual address, whichis then translated, as described above, using address translationstructures 384 to obtain host page frame real address 374 f The hostpage frame real address is then combined (e.g., concatenated) with theoffset (e.g., bits 52-63) of the host virtual address to obtain thefinal host real address. This completes translation of a guest virtualaddress to a host real address.

Although in the above examples translation starts at the region firsttable, this is only one example. Translation may start at any level foreither the guest or the host.

Further, in one embodiment, to improve address translation, a virtualaddress to real or absolute address translation mapping may be stored inan entry of a structure associated with address translation, such as atranslation look-aside buffer (TLB). The TLB is a cache used by thememory management hardware to improve virtual address translation speed.The next time translation for a virtual address is requested, the TLBwill be checked and if it is in the TLB, there is a TLB hit and the realor absolute address is retrieved therefrom. Otherwise, a page walk isperformed, as described above.

In one example, as depicted in FIG. 3C, a translation look-aside buffer390 may include one or more entries 392. An entry may be for a host orfor a guest of the computing environment, and may be marked as such withan indicator (e.g., H/G indicator 394). For instance, if H/G 394 is setto one, then it is a host entry, and if set to zero, it is a guestentry. Further, an entry may be associated with a page table entry, aregion table entry or a segment table entry of the address translationtables. Many implementations of a translation look-aside buffer arepossible.

As indicated, guest translations may be included in the TLB. Theseentries may be composite guest/host entries which implicitly include oneor more host translations. For example, a guest virtual TLB entry maybuffer the entire translation from the initial guest virtual addressdown to the final host real or absolute address. In this case, the guestTLB entry implicitly includes all intermediate host translations 372,376, 378, 380 and 382, as well as the final host translation 384, asdescribed in FIG. 3B above. In another example, a hierarchical TLB maycontain an entry in a first level of the TLB which buffers a translationfrom the initial guest virtual address down to the associated origin ofthe guest page table 322 and a separate entry from a second level of theTLB which buffers the translation from the guest page table entryaddress down to the final host real or absolute address. In thisexample, guest entries in the first level of the TLB implicitly includeintermediate host translations 372, 376, 378 and 380 which correspond tothe host translations which back guest region and segment tables, andguest entries in the second level implicitly include intermediate hosttranslation 382 which backs the guest page table and final hosttranslation 384, as described in FIG. 3B. Many implementations of atranslation look-aside buffer are possible.

In accordance with an aspect of the present invention, when pages arepaged-out due to physical memory constraints, page table entries of thepaged-out pages are invalidated and corresponding translation look-asidebuffer (or other structures associated with address translation) entriesare purged.

As examples, there are two types of TLB purges/invalidates: local andbroadcast. From a software perspective, a local purge affects only thevirtual CPU (vCPU) of the issuing processor (thread), and a broadcastpurge affects the configuration (all threads of all cores) of theissuing processor. For local purges, although the TLB is maintained on avirtual CPU (thread) basis from an architecture and softwareperspective, it is maintained on a physical CPU basis from a machineperspective. This means that whenever the software (e.g., program)issues a local purge, it is the responsibility of the machine to makesure that the local purge is propagated to all physical processors(threads) that might have TLB entries pertaining to that vCPU. For guestpurge requests, this management is currently performed by the StartInterpretative Execution (SIE) entry millicode whenever a guest vCPU isre-dispatched on a different physical processor.

In one embodiment, when a local invalidate/purge is performed, oftenonly a subset of entries need to be purged. For example, an InvalidatePage Table Entry (IPTE) instruction only purges entries associated witha particular page index (PX) and page table origin (PTO). Since a largenumber of local purges may be performed while a vCPU is dispatched on asingle physical processor (thread), the various different TLB entriesthat are affected are not tracked. As a result, when that vCPU isdispatched on a different physical processor (thread), all TLB entriesassociated with the vCPU are purged. This may result in purging moreentries than actually necessary.

As indicated above, one instruction used to perform the purging is anInvalidate Page Table Entry (IPTE) instruction, an example of which isdescribed with reference to FIGS. 4A-4E. The IPTE instructioninvalidates specified page table entries and purges related TLB entries,as described herein.

Referring initially to FIG. 4A, in one example, an Invalidate Page TableEntry (IPTE) instruction 400 includes an opcode field 402 that includesan operation code specifying an invalidate page table entry operation; afirst register field (R₃) 404; a mask field (M₄) 406; a second registerfield (R₁) 408; and a third register field (R₂) 410, each of which isdescribed below.

Referring to FIG. 4B, the register designated by register field (R₃) 404provides certain information, including, for instance, a count (orrange) of additional entries 454, if any, to be invalidated.

Referring to FIG. 4C, mask field (M₄) 406 includes a local clearingcontrol 460, which can be used, in conjunction with other parameters, todetermine if the command is broadcast to all CPUs in the configurationor sent just to the issuing (local) CPU.

With reference to FIG. 4D, second register field (R₁) 408 specifies aregister used to indicate a page table origin (PTO) 470 of a page ofmemory to be invalidated; and referring to FIG. 4E, third register field(R₂) 410 specifies a register used to indicate a page index (PX) 480 ofa page of memory to be invalidated.

In general operation of IPTE, the designated page table entries areinvalidated and the translation look-aside buffers (or other suchstructures) in the physical processor (thread) performing the operationand/or other physical processors (threads) in the configuration arecleared of the associated entries. Local clearing control 460 controlswhether only the TLB in the local CPU (thread) is cleared or whether theTLBs in all of the CPUs of the configuration (i.e., all threads of allcores) are cleared.

In particular, as used herein, the term “specified CPU or CPUs” has thefollowing meaning for the scope of TLBs affected by this instruction, asimplemented in the z/Architecture, as one example:

-   -   When the local TLB clearing facility is not installed, or when        the facility is installed and the local clearing control (LC)        bit in the M₄ field is zero, the term “specified CPU and CPUs”        means all of the CPUs in the configuration (i.e., all of the        threads of all cores of the configuration).    -   When the local TLB clearing facility is installed and the LC bit        in the M₄ field is one, the term “specified CPU or CPUs” means        only the CPU executing the IPTE instruction (the local CPU; the        local thread). The TLBs in all other CPUs in the configuration        (i.e., all other threads of all cores) may not be affected.

There may be additional control bits, typically defined by the host,that might also indicate that a vCPU does not need to broadcast anypurge requests. One such control bit, for example, would indicate thatthis vCPU is configured as a uni-processor (i.e., the only virtual CPUin the guest configuration) and, if so, then a local purge may be issuedby the processor even though the IPTE instruction has specified abroadcast purge. If this is the case, then the optimization described byan aspect of the invention would also apply as if the local TLB clearingis installed and the LC bit is set.

The designated page table entries are invalidated (e.g., a page invalidindicator within the appropriate page table entries is set to one), andthe translation look-aside buffers (TLBs) in the specified CPU (thread)or CPUs (threads) in the configuration are cleared of the associatedentries.

The contents of the general register R₁ have the format of a segmenttable entry, with only the page table origin used. The contents ofgeneral register R₂ have the format of a virtual address, with only thepage index used. The contents of fields that are not part of the pagetable origin or page index are ignored.

When the IPTE range facility is not installed, or when the R₃ field iszero, the single page table entry designated by the first and secondoperands (registers specified by R₁ and R₂, respectively) isinvalidated.

When the IPTE range facility is installed and the R₃ field is nonzero,bits 56-63 (e.g., additional entries 454) of general register R₃ containan unsigned binary integer specifying the count of additional page tableentries to be invalidated. Therefore, the number of page-table entriesto be invalidated is 1-256, corresponding to a value of 0-255 in bits56-63 of the register.

When the IPTE range facility is not installed, the R₃ field is ignoredbut should contain zeros; otherwise, the program may not operatecompatibly in the future.

The bits of the M₄ field 406 are as follows, in one example:

-   -   Reserved: Bits 0-2 are reserved. Reserved bit positions of the        M₄ field are ignored but should contain zeros; otherwise, the        program may not operate compatibly in the future.    -   Local Clearing Control (LC) 460. When the local TLB clearing        facility is installed, the LC bit, e.g., bit 3 of the M₄ field,        controls whether only the TLB in the local CPU (thread) is        cleared or whether the TLBs in all CPUs (threads) of the        configuration are cleared. When the local TLB clearing facility        is not installed, bit 3 of the M₄ field is reserved.

Page table origin 470 in general register R₁ and page index 480 ingeneral register R₂ designate a page table entry, following the dynamicaddress translation rules for page table lookup. The page table origine.g., is treated as a 64-bit address, and the addition is performed byusing the rules for 64-bit address arithmetic, regardless of the currentaddressing mode, which is specified by bits 31 and 32 of the currentprogram status word (PSW). A carry out of bit position 0 as a result ofthe addition of the page index and page table origin is not to occur.The address formed from these two components is a real or absoluteaddress. The page invalid bit of this page table entry is set to one.During this procedure, in one example, the page table entry is notinspected for whether the page invalid bit is already one or for formaterrors. Additionally, the page frame real address contained in the entryis not checked for an addressing exception in this example.

When the IPTE range facility is installed and the R₃ field is nonzero,the instruction is interruptible, and processing is as follows, in oneembodiment:

-   -   1. The invalidation process described above is repeated for each        subsequent entry in the page table until either the number of        additional entries specified in bits 56-63 of general register        R₃ have been invalidated or an interruption occurs.    -   2. The page index in bits 44-51 of general register R₂ is        incremented by the number of page table entries that were        invalidated; a carry out of bit position 44 of general register        R₂ is ignored.    -   3. The additional entry count in bits 56-63 of general register        R₃ is decremented by the number of page table entries that were        invalidated.

Therefore, when the IPTE range facility is installed, the R₃ field isnonzero, and an interruption occurs (other than one that causestermination), general registers R₂ and R₃ have been updated, so that theinstruction, when re-executed, resumes at the point of interruption.

When the IPTE range facility is not installed, or when the R₃ field iszero, the contents of registers R₂ and R₃ remain unchanged.

For each page table entry that is invalidated, the entire page tableentry appears to be fetched concurrently from storage as observed byother CPUs. Subsequently, the byte containing the page invalid bit isstored. The fetch access to each page table entry is subject to keycontrolled protection, and the store access is subject to key controlledprotection and low address protection.

A serialization function is performed before the operation begins andagain after the operation is completed. As is the case for otherserialization operations, this serialization applies only to this CPU;other CPUs are not necessarily serialized.

If no exceptions are recognized, this CPU (thread) clears selectedentries from its TLB. Then, if the local TLB clearing facility is notinstalled, or if the facility is installed and the LC bit in the M₄field is zero, this CPU signals all CPUs in the configuration (i.e., allthreads in all cores) to clear selected entries from their TLBs. Foreach page table entry invalidated, each affected TLB is cleared of atleast those entries that have been formed using all of the following:

-   -   The page table origin specified by general register R₁    -   The page index specified by general register R₂    -   The page frame real address contained in the designated page        table entry.

The execution of Invalidate Page Table Entry is not completed on the CPUwhich executes it until the following occur, in one embodiment:

-   -   1. All page table entries corresponding to the specified        parameters have been invalidated.    -   2. All entries corresponding to the specified parameters have        been cleared from the TLB of this CPU. When the local TLB        clearing facility is installed and the LC bit in the M₄ field is        one, the execution of Invalidate Page Table entry is complete at        this point and the following step is not performed.    -   3. When the local TLB clearing facility is not installed, or        when the facility is installed and the LC bit in the M₄ field is        zero, all other CPUs in the configuration have completed any        storage accesses, including the updating of the change and        reference bits, by using TLB entries corresponding to the        specified parameters.

When the IPTE range facility is installed, the R₃ field is nonzero, andthe page index in general register R₂ plus the additional entry count ingeneral register R₃ is greater than 255, a specification is recognized.

The operation is suppressed on all addressing and protection exceptions.

Condition Code: The code remains unchanged.

The Invalidate Page Table Entry instruction described above is only oneexample of an instruction requesting purging. Other instructions mayalso be used including, for instance, an Invalidate DAT Table Entry(IDTE) instruction and a Compare and Replace DAT Table Entry (CRDTE)instruction, as well as others. Further, the purge request may beprovided or obtained in other ways.

The Invalidate DAT Table Entry (IDTE) instruction is similar to the IPTEinstruction, except that designated region table or segment tableentries (instead of page table entries) are invalidated and theassociated TLB entries are purged. The IDTE instruction has a formatthat includes, e.g., an R₃ field specifying one register; an M₄ fieldspecifying a mask; an R₁ field specifying another register; and an R₂field specifying yet a further register, each of which is used toinvalidate/purge particular entries.

Similarly, the Compare and Replace DAT Table Entry (CRDTE) instruction(having a similar format of R₃, M₄, R₁, and R₂) may be used to purgeguest TLB entries of associated page table, segment table and/or regiontable entries being compared and replaced.

Other instructions may also be used; as well as other types of requests.Many variations are possible.

As described above, the invalidation instructions invalidate entries ofaddress translation tables (e.g., page table entries, segment tableentries, and/or region table entries), as well as purge correspondingentries of structures associated with address translation (e.g.,translation look-aside buffers). Further details regarding the purgingof entries of structures associated with address translation aredescribed below.

One embodiment of a current implementation for servicing a guest purgerequest is described with reference to FIG. 5. In one example, a guestexecuting on a hardware thread issues an invalidation or purge request,STEP 500. For instance, a guest issues an IPTE instruction. Adetermination is made as to whether the purge request is a localrequest, INQUIRY 502. For instance, local clearing control 460 of maskfield 406 of the IPTE instruction is checked to see if it is a localrequest. If local clearing control 460 is set to one, it is a localrequest.

Based on the purge request being a local request, relevant entries inthe TLB of the initiating guest hardware thread are purged, STEP 504. Inthe case of IPTE, for example, the relevant entries include all guestentries whose PX and PTO match those specified by the IPTE instruction.The relevant entries are selective guest entries, e.g., based on thepage being invalidated, rather than all guest entries regardless of thepage being invalidated.

Otherwise, if the purge request is not a local request, INQUIRY 502,then the IPTE purge request is broadcast to all processors in theconfiguration (i.e., all threads in all cores of the configuration) andrelevant entries on all the TLBs in the configuration are purged, STEP506. Subsequent to purging the entries, STEP 504, 506, executioncontinues, STEP 508.

In accordance with an aspect of the present invention, the above processfurther includes increasing the scope of the local purges, as describedwith reference to FIG. 6. Referring to FIG. 6, in one example, a guestexecuting on a hardware thread of a particular physical core issues aninvalidation or purge request, e.g., an IPTE instruction, STEP 600. Adetermination is made as to whether the purge request is a localrequest, INQUIRY 602. If it is a local request (e.g., local clearingcontrol 460 is set to one), then relevant entries in the TLBs of a setof hardware threads of the machine configuration are purged, rather thanjust the relevant entries of the initiating thread, STEP 604. The set ofhardware threads may be determined, in one example, by the topology ofthe system. The set may include, for example, some or all of the threadsof the physical core where the request was initiated, some or all of thethreads of all of the physical cores of a physical processor chip wherethe request was initiated, or some or all of the threads of a pluralityof physical processor chips. This set is defined by the machine forevery local purge.

Otherwise, if it is not a local request, then relevant entries on all ofthe hardware threads in the configuration are purged based on abroadcast purge, STEP 606. Subsequent to purging the entries, STEP 604,606, execution continues, STEP 608.

In one particular embodiment, the set includes all the threads of theinitiating core. By increasing the scope of local purging to entries inthe TLBs on all (or a subset) of the threads on a single core, thepenalty of dispatching a given guest vCPU on a different thread within aphysical core is decreased.

Moreover, although the particular embodiment purges, based on a localpurge request, TLB entries from the threads of a single core, in furtherexamples, TLB entries from threads of multiple cores may be purged,based on the local request. Again, the set may be defined as above. Byincreasing the scope of local purging to the threads of a defined set,as described above, the penalty of dispatching a given vCPU on adifferent thread within a set of threads is decreased. Further, thepurging of all entries at Start Interpretative Execution (SIE) entrywhen a guest vCPU moves to a different hardware thread may beeliminated; thus, increasing system performance.

In addition to the above, the invalidating/purging may also be performedon entry into Start Interpretative Execution (SIE) mode. One embodimentof a conventional approach for purging based on SIE entry is describedwith reference to FIG. 7. This logic is performed by the hardware threadentering SIE.

Referring to FIG. 7, initially, a determination is made as to whether alocal guest purge has been specified by the host, e.g., in the statedescription, INQUIRY 702. If the host did not specify a local guestpurge, then a further determination is made as to whether the guest thatis entering SIE last ran on this hardware thread, INQUIRY 704. If theguest did last run on this hardware thread, INQUIRY 704, then no purgeis performed and execution continues, STEP 708.

Otherwise, if the guest did not last run on this hardware thread,INQUIRY 704, or if the host did request a local guest purge, INQUIRY702, then all guest entries (i.e., not selective guest entries, but allthe entries of the guest) from this hardware thread's TLB are purged,STEP 706. Execution continues, STEP 708. This purge is done to ensurethat any TLB entries that may have been invalidated by a local purgewhen that guest vCPU was running on a different hardware thread will bepurged as is defined by the architecture.

In accordance with an aspect of the present invention, the above SIEprocessing further checks whether the guest last ran on a thread withina defined set of threads rather than checking if it last ran on theinitiating hardware thread, and processing proceeds based thereon. Oneembodiment of this logic is described with reference to FIG. 8. Thislogic is performed by the hardware thread entering SIE.

Referring to FIG. 8, initially, a determination is made as to whether alocal guest purge has been specified by the host (e.g., in the statedescription), INQUIRY 802. If the host did not request a local guestpurge, then a further determination is made as to whether the guest lastran on a thread within the set of threads that contain the threadissuing SIE (as opposed to checking whether it last ran on this thread),INQUIRY 804. If the guest did last run on a thread within the set ofthreads, INQUIRY 804, then execution continues, STEP 808. Otherwise, ifthe guest did not last run on this set of threads, INQUIRY 804, or thehost did request a local guest purge, INQUIRY 802, then all of the guestentries (that is, all entries of the guest, rather than, e.g., selectiveentries associated with a particular page) of the TLB on all of thethreads of this set of threads are purged, STEP 806. This means thatwhen a guest moves between threads within a set of threads, SIE entry nolonger purges the guest TLB. This purge can be eliminated, since anylocal purge that was issued while the guest was running on anotherhardware thread was serviced on this thread when the local purge issued.This decreases purging and may increase overall system performance.

In a further aspect, complete purges are tracked, and therefore, thescope of local purges is increased, based on an indication that a fulllocal purge has not already been performed while this vCPU (guest) isrunning on the hardware thread. This is further described with referenceto FIGS. 9-10.

Referring to FIG. 9, another embodiment of logic associated with a guestrequest to purge is described. Initially, a guest executing on ahardware thread of a physical core issues an invalidation or purgerequest (e.g., an IPTE instruction), STEP 900. A determination is madeas to whether the request is a local request (e.g., is local clearingcontrol 460 set to one), INQUIRY 902. If the request is not a localrequest, then relevant entries (or all guest entries if the purgerequest is a full purge request) on all hardware threads in theconfiguration (i.e., all hardware threads of all cores of theconfiguration) are purged, STEP 904, and execution continues, STEP 916.However, if the request is a local request, then a further determinationis made as to whether a complete purge of other thread(s) within the setof threads has already been done (e.g., a Purge Done indicator storedin, e.g., memory is checked), INQUIRY 906. If a complete purge has beendone previously, then relevant entries (or all for a full purge request)in the TLB on the hardware thread initiating the purge are purged, STEP908, and execution continues, STEP 916. Otherwise, if a complete purgehas not been done, then relevant entries (or all for a full purgerequest) in the TLBs on all threads of the set of threads are purged,STEP 910.

Thereafter, a determination is made as to whether the request was a fullpurge request (not a request of selective entries, but of all guestentries), INQUIRY 912. If not, then execution continues, STEP 916.However, if the request was a full purge request, INQUIRY 912, then thePurge_Done indicator is set (e.g., to one), STEP 914. Execution thencontinues, STEP 916.

FIG. 10 depicts another embodiment of purging on SIE entry. This logicis performed by the thread entering SIE. Initially, the Purge_Doneindicator is reset (e.g., set to zero) on SIE entry, STEP 1000. Adetermination is made as to whether a local guest purge is specified bythe host (e.g., in state description), INQUIRY 1002. If the host did notspecify a local guest purge, then a further determination is made as towhether the guest last ran on the set of threads, INQUIRY 1004. If theguest did last run on the set of threads, INQUIRY 1004, no purge isperformed, and execution continues, STEP 1010. Otherwise, if the guestthread did not last run on the set of threads, INQUIRY 1004, or the hostdid specify a local guest purge, INQUIRY 1002, then all guest entries(not just the relevant entries) in the TLBs on all threads of this setof threads are purged, STEP 1006, and the Purge_Done indicator is set(e.g., to one), STEP 1008. Processing then continues to STEP 1010.

Described above are techniques for increasing the scope of local purges,thus decreasing the number of SIE purges, and increasing overall systemperformance. In further embodiments, the scope can be increased to anyphysical processor granularity where the overhead of expanding the scopeof the local purge is small enough to see benefit from reducing theresidual penalty of the SIE entry purge, not necessarily to all threadsin the core, and not necessarily limited to the threads on one core. Thegranularity of processor dispatch affinity that can be maintained by thehypervisor would also be a factor in determining the optimum increasedscope of local invalidates.

Described in detail above are capabilities for increasing the scope oflocal purges, which may eliminate or reduce the more drastic purge ofall entries at SIE entry when the guest moves to a different thread. Inaddition, aspects of this invention may help provide additionalflexibility to the hypervisor dispatch logic by decreasing the machinepenalty of dispatching a given guest vCPU on a different thread.

Moreover, in an environment where the hypervisor does not maintaindispatch affinity between threads on a core and the guest uses localpurge/invalidate commands to manage their TLB, a performance benefit maybe realized by not purging the entire TLB as the vCPU moves back andforth between the threads.

Machine topology and overhead of signaling (e.g., issuing IPTE),transparent to the software, are used to determine the scope of purges.Further, machine-dependent hardware adjustments are allowed to reduceand improve purge signaling requirements between threads.

Further details regarding purge processing are described with referenceto FIGS. 11A-11C. Referring initially to FIG. 11A, a hardware thread ofa physical core of a machine configuration issues a purge request(1100). A determination is made as to whether the purge request is alocal request (1102). Based on the purge request being a local request,one or more entries of a structure associated with address translation(e.g., a translation look-aside buffer) are purged on at least multiplehardware threads of a set of hardware threads of the machineconfiguration (1104). As one example, the purging of the one or moreentries of the structure associated with address translation includespurging one or more entries of the structure associated with addresstranslation associated with a particular page of memory specified by thepurge request (1106).

In one embodiment, the issuing of the purge request includes issuing aninvalidate instruction, which indicates the purge request (1108) FIG.11B. The invalidate instruction includes, for instance, an invalidatepage table entry instruction, an invalidate dynamic address translationtable entry instruction, or a compare and replace dynamic addresstranslation table entry instruction (1110).

In a further embodiment, based on the purge request being a localrequest, a check is made as to whether a purge has already beenperformed on the hardware threads of the set of hardware threads exceptfor the hardware thread issuing the purge request (1112). Based on thechecking indicating the purge has not already been performed, thepurging is performed (1114).

Further, in one example, based on performing the purging, adetermination is made as to whether the purge request is a request topurge specific guest entries (1116). Based on the purge request notbeing a request to purge specific guest entries, a purge done indicatoris set (1118).

In yet another embodiment, the hardware thread is entering startinterpretative execution (SIE) on the physical core (1120), FIG. 11C.Based on entering SIE, a determination is made as to whether a guestexecuting on the hardware thread last ran on a thread within the set ofthreads (1122). Based on determining the guest last ran on a threadwithin the set of threads, refrain from purging guest entries of thestructure associated with address translation (1124).

In a further embodiment, based on determining the guest did not last runon a thread within the set of threads, guest entries of the structureassociated with address translation are purged (1125), and a purge doneindicator is set (1126).

As one example, the purging on the at least multiple threads reducespurging to be performed on start interpretative execution entry of thehardware thread (1130).

It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g. networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based email). Theconsumer does not manage or control the underlying cloud infrastructureincluding network, servers, operating systems, storage, or evenindividual application capabilities, with the possible exception oflimited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forloadbalancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring now to FIG. 12, a schematic of an example of a cloud computingnode is shown. Cloud computing node 10 is only one example of a suitablecloud computing node and is not intended to suggest any limitation as tothe scope of use or functionality of embodiments of the inventiondescribed herein. Regardless, cloud computing node 10 is capable ofbeing implemented and/or performing any of the functionality set forthhereinabove.

In cloud computing node 10 there is a computer system/server 12, whichis operational with numerous other general purpose or special purposecomputing system environments or configurations. Examples of well-knowncomputing systems, environments, and/or configurations that may besuitable for use with computer system/server 12 include, but are notlimited to, personal computer systems, server computer systems, thinclients, thick clients, handheld or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 12 may be described in the general context ofcomputer system-executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 12 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 12, computer system/server 12 in cloud computing node10 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 12 may include, but are not limitedto, one or more processors or processing units 16, a system memory 28,and a bus 18 that couples various system components including systemmemory 28 to processor 16.

Bus 18 represents one or more of any of several types of bus structures,including a memory bus or memory controller, a peripheral bus, anaccelerated graphics port, and a processor or local bus using any of avariety of bus architectures. By way of example, and not limitation,such architectures include Industry Standard Architecture (ISA) bus,Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, VideoElectronics Standards Association (VESA) local bus, and PeripheralComponent Interconnect (PCI) bus.

Computer system/server 12 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 12, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 28 can include computer system readable media in the formof volatile memory, such as random access memory (RAM) 30 and/or cachememory 32. Computer system/server 12 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 34 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 18 by one or more datamedia interfaces. As will be further depicted and described below,memory 28 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 40, having a set (at least one) of program modules 42,may be stored in memory 28 by way of example, and not limitation, aswell as an operating system, one or more application programs, otherprogram modules, and program data. Each of the operating system, one ormore application programs, other program modules, and program data orsome combination thereof, may include an implementation of a networkingenvironment. Program modules 42 generally carry out the functions and/ormethodologies of embodiments of the invention as described herein.

Computer system/server 12 may also communicate with one or more externaldevices 14 such as a keyboard, a pointing device, a display 24, etc.;one or more devices that enable a user to interact with computersystem/server 12; and/or any devices (e.g., network card, modem, etc.)that enable computer system/server 12 to communicate with one or moreother computing devices. Such communication can occur via Input/Output(I/O) interfaces 22. Still yet, computer system/server 12 cancommunicate with one or more networks such as a local area network(LAN), a general wide area network (WAN), and/or a public network (e.g.,the Internet) via network adapter 20. As depicted, network adapter 20communicates with the other components of computer system/server 12 viabus 18. It should be understood that although not shown, other hardwareand/or software components could be used in conjunction with computersystem/server 12. Examples, include, but are not limited to: microcode,device drivers, redundant processing units, external disk drive arrays,RAID systems, tape drives, and data archival storage systems, etc.

Referring now to FIG. 13, illustrative cloud computing environment 50 isdepicted. As shown, cloud computing environment 50 comprises one or morecloud computing nodes 10 with which local computing devices used bycloud consumers, such as, for example, personal digital assistant (PDA)or cellular telephone 54A, desktop computer 54B, laptop computer 54C,and/or automobile computer system 54N may communicate. Nodes 10 maycommunicate with one another. They may be grouped (not shown) physicallyor virtually, in one or more networks, such as Private, Community,Public, or Hybrid clouds as described hereinabove, or a combinationthereof. This allows cloud computing environment 50 to offerinfrastructure, platforms and/or software as services for which a cloudconsumer does not need to maintain resources on a local computingdevice. It is understood that the types of computing devices 54A-N shownin FIG. 13 are intended to be illustrative only and that computing nodes10 and cloud computing environment 50 can communicate with any type ofcomputerized device over any type of network and/or network addressableconnection (e.g., using a web browser).

Referring now to FIG. 14, a set of functional abstraction layersprovided by cloud computing environment 50 (FIG. 13) is shown. It shouldbe understood in advance that the components, layers, and functionsshown in FIG. 14 are intended to be illustrative only and embodiments ofthe invention are not limited thereto. As depicted, the following layersand corresponding functions are provided:

Hardware and software layer 60 includes hardware and softwarecomponents. Examples of hardware components include mainframes 61; RISC(Reduced Instruction Set Computer) architecture based servers 62;servers 63; blade servers 64; storage devices 65; and networks andnetworking components 66. In some embodiments, software componentsinclude network application server software 67 and database software 68.

Virtualization layer 70 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers71; virtual storage 72; virtual networks 73, including virtual privatenetworks; virtual applications and operating systems 74; and virtualclients 75.

In one example, management layer 80 may provide the functions describedbelow. Resource provisioning 81 provides dynamic procurement ofcomputing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricing 82provide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal 83 provides access to the cloud computing environment forconsumers and system administrators. Service level management 84provides cloud computing resource allocation and management such thatrequired service levels are met. Service Level Agreement (SLA) planningand fulfillment 85 provide pre-arrangement for, and procurement of,cloud computing resources for which a future requirement is anticipatedin accordance with an SLA.

Workloads layer 90 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation 91; software development and lifecycle management 92; virtualclassroom education delivery 93; data analytics processing 94;transaction processing 95; and purge processing 96.

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, configuration data for integrated circuitry, oreither source code or object code written in any combination of one ormore programming languages, including an object oriented programminglanguage such as Smalltalk, C++, or the like, and procedural programminglanguages, such as the “C” programming language or similar programminglanguages. The computer readable program instructions may executeentirely on the user's computer, partly on the user's computer, as astand-alone software package, partly on the user's computer and partlyon a remote computer or entirely on the remote computer or server. Inthe latter scenario, the remote computer may be connected to the user'scomputer through any type of network, including a local area network(LAN) or a wide area network (WAN), or the connection may be made to anexternal computer (for example, through the Internet using an InternetService Provider). In some embodiments, electronic circuitry including,for example, programmable logic circuitry, field-programmable gatearrays (FPGA), or programmable logic arrays (PLA) may execute thecomputer readable program instructions by utilizing state information ofthe computer readable program instructions to personalize the electroniccircuitry, in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

In addition to the above, one or more aspects may be provided, offered,deployed, managed, serviced, etc. by a service provider who offersmanagement of customer environments. For instance, the service providercan create, maintain, support, etc. computer code and/or a computerinfrastructure that performs one or more aspects for one or morecustomers. In return, the service provider may receive payment from thecustomer under a subscription and/or fee agreement, as examples.Additionally or alternatively, the service provider may receive paymentfrom the sale of advertising content to one or more third parties.

In one aspect, an application may be deployed for performing one or moreembodiments. As one example, the deploying of an application comprisesproviding computer infrastructure operable to perform one or moreembodiments.

As a further aspect, a computing infrastructure may be deployedcomprising integrating computer readable code into a computing system,in which the code in combination with the computing system is capable ofperforming one or more embodiments.

As yet a further aspect, a process for integrating computinginfrastructure comprising integrating computer readable code into acomputer system may be provided. The computer system comprises acomputer readable medium, in which the computer medium comprises one ormore embodiments. The code in combination with the computer system iscapable of performing one or more embodiments.

Although various embodiments are described above, these are onlyexamples. For example, computing environments of other architectures canbe used to incorporate and use one or more embodiments. Further,different instructions, instruction formats, instruction fields and/orinstruction values may be used. Many variations are possible.

Further, other types of computing environments can benefit and be used.As an example, a data processing system suitable for storing and/orexecuting program code is usable that includes at least two processorscoupled directly or indirectly to memory elements through a system bus.The memory elements include, for instance, local memory employed duringactual execution of the program code, bulk storage, and cache memorywhich provide temporary storage of at least some program code in orderto reduce the number of times code must be retrieved from bulk storageduring execution.

Input/Output or I/O devices (including, but not limited to, keyboards,displays, pointing devices, DASD, tape, CDs, DVDs, thumb drives andother memory media, etc.) can be coupled to the system either directlyor through intervening I/O controllers. Network adapters may also becoupled to the system to enable the data processing system to becomecoupled to other data processing systems or remote printers or storagedevices through intervening private or public networks. Modems, cablemodems, and Ethernet cards are just a few of the available types ofnetwork adapters.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises” and/or “comprising”,when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below, if any, areintended to include any structure, material, or act for performing thefunction in combination with other claimed elements as specificallyclaimed. The description of one or more embodiments has been presentedfor purposes of illustration and description, but is not intended to beexhaustive or limited to in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the art. Theembodiment was chosen and described in order to best explain variousaspects and the practical application, and to enable others of ordinaryskill in the art to understand various embodiments with variousmodifications as are suited to the particular use contemplated.

What is claimed is:
 1. A computer program product for facilitatingprocessing in a computing environment, said computer program productcomprising: a computer readable storage medium readable by a processingcircuit and storing instructions for execution by the processing circuitfor performing a method comprising: issuing, by a hardware thread of aphysical core of a machine configuration, a purge request; determiningwhether the purge request is a local request; and purging, based on thepurge request being a local request, one or more entries of a structureassociated with address translation on at least multiple hardwarethreads of a set of hardware threads of the machine configuration. 2.The computer program product of claim 1, wherein the purging the one ormore entries of the structure associated with address translationincludes purging one or more entries of the structure associated withaddress translation associated with a particular page of memoryspecified by the purge request.
 3. The computer program product of claim1, wherein the structure associated with address translation comprises atranslation look-aside buffer.
 4. The computer program product of claim1, wherein the issuing the purge request includes issuing an invalidateinstruction, the invalidate instruction indicating the purge request. 5.The computer program product of claim 4, wherein the invalidateinstruction includes an instruction selected from the group consistingof: an invalidate page table entry instruction, an invalidate dynamicaddress translation table entry instruction, and a compare and replacedynamic address translation table entry instruction.
 6. The computerprogram product of claim 1, wherein the method further comprises:checking, based on the purge request being a local request, whether apurge has already been performed on the hardware threads of the set ofhardware threads except for the hardware thread issuing the purgerequest; and performing the purging, based on the checking indicatingthe purge has not already been performed.
 7. The computer programproduct of claim 6, wherein the method further comprises: determining,based on performing the purging, whether the purge request is a requestto purge specific guest entries; and setting a purge done indicatorbased on the purge request not being a request to purge specific guestentries.
 8. The computer program product of claim 1, wherein the methodfurther comprises: entering, by the hardware thread, StartInterpretative Execution (SIE) on the physical core; determining, basedon entering SIE, whether a guest executing on the hardware thread lastran on a thread within the set of threads; and refraining, based ondetermining the guest last ran on a thread within the set of threads,from purging guest entries of the structure associated with addresstranslation.
 9. The computer program product of claim 8, wherein themethod further comprises: purging, based on determining the guest didnot last run on a thread within the set of threads, guest entries of thestructure associated with address translation on threads of the set ofthreads; and setting a purge done indicator, based on purging the guestentries on the threads of the set of entries.
 10. The computer programproduct of claim 1, wherein the purging on the at least multiple threadsreduces purging to be performed on Start Interpretative Execution entryof the hardware thread.
 11. A computer system for facilitatingprocessing in a computing environment, said computer system comprising:a memory; and a hardware thread in communication with the memory,wherein the computer system is configured to perform a method, saidmethod comprising: issuing, by the hardware thread of a physical core ofa machine configuration, a purge request; determining whether the purgerequest is a local request; and purging, based on the purge requestbeing a local request, one or more entries of a structure associatedwith address translation on at least multiple hardware threads of a setof hardware threads of the machine configuration.
 12. The computersystem of claim 11, wherein the method further comprises: checking,based on the purge request being a local request, whether a purge hasalready been performed on the hardware threads of the set of hardwarethreads except for the hardware thread issuing the purge request; andperforming the purging, based on the checking indicating the purge hasnot already been performed.
 13. The computer system of claim 12, whereinthe method further comprises: determining, based on performing thepurging, whether the purge request is a request to purge specific guestentries; and setting a purge done indicator based on the purge requestnot being a request to purge specific guest entries.
 14. The computersystem of claim 11, wherein the method further comprises: entering, bythe hardware thread, Start Interpretative Execution (SIE) on thephysical core; determining, based on entering SIE, whether a guestexecuting on the hardware thread last ran on a thread within the set ofthreads; and refraining, based on determining the guest last ran on athread within the set of threads, from purging other guest entries ofthe structure associated with address translation.
 15. The computersystem of claim 11, wherein the purging on the at least multiple threadsreduces purging to be performed on Start Interpretative Execution entryof the hardware thread.
 16. A computer-implemented method offacilitating processing in a computing environment, saidcomputer-implemented method comprising: issuing, by a physical thread ofa physical core of a machine configuration, a purge request; determiningwhether the purge request is a local request; and purging, based on thepurge request being a local request, one or more entries of a structureassociated with address translation on at least multiple hardwarethreads of a set of hardware threads of the machine configuration. 17.The computer-implemented method of claim 16, further comprising:checking, based on the purge request being a local request, whether apurge has already been performed on the hardware threads of the set ofhardware threads except for the hardware thread issuing the purgerequest; and performing the purging, based on the checking indicatingthe purge has not already been performed.
 18. The computer-implementedmethod of claim 17, further comprising: determining, based on performingthe purging, whether the purge request is a request to purge specificguest entries; and setting a purge done indicator based on the purgerequest not being a request to purge specific guest entries.
 19. Thecomputer-implemented method of claim 16, wherein the method furthercomprises: entering, by the hardware thread, Start InterpretativeExecution (SIE) on the physical core; determining, based on enteringSIE, whether a guest executing on the hardware thread last ran on athread within the set of threads; and refraining, based on determiningthe guest last ran on a thread within the set of threads, from purgingguest entries of the structure associated with address translation. 20.The computer-implemented method of claim 16, wherein the purging on theat least multiple threads reduces purging to be performed on StartInterpretative Execution entry of the hardware thread.